1. Field of the Invention
The present invention relates generally to the excavation of solid substrates, and particularly to a method for wire saw excavation wherein a single downhole is formed into the substrate and a wire saw is used to cut a core from the substrate from the single downhole.
2. Description of the Related Art
A number of different methods have been developed in the past for earth excavation and tunneling. While the earliest tunnels and excavations were carried out using hand tools, a more practicable approach is by means of mechanized tools and equipment and/or the use of explosives. However, explosives can be difficult to control accurately, and not only destroy the core material being removed, but may also fracture and weaken the surrounding substrate. This requires considerably more time, effort, and cost to reinforce the weakened substrate around the hole formed by the detonated explosive charge. While mechanized equipment does not generally cause so much damage to the surrounding substrate, it generally results in the destruction of the core material. This may be an important consideration in such industries as granite quarrying and the like.
More recently, methods have been developed for the excavation of hard materials by means of wire saws. Wire saws comprise heavy cables having spaced cutting elements installed along the cables, which are driven by machinery similar to a chain saw or the like. Wire saws greatly reduce the damage both to the core and to the surrounding substrate (e.g., rock, concrete, etc.), reduce the energy expended during the excavation, and further reduce the time and effort required for creating the finalized shape of the excavation and/or core. However, conventionally it is necessary to bore or otherwise form a plurality of downholes into the substrate in order to introduce distal wire saw guides (pulleys, etc.) to the bottom of the intended excavation. The wire saw is then run around two or more such pulleys to make the cut in the substrate to form the core to be removed. The need for the formation of multiple downholes in the substrate requires significantly more time and effort than would otherwise be required if only a single downhole were needed.
Thus, a method for wire saw excavation solving the aforementioned problems is desired.